In recent years, under circumstances where reductions in size, weight, and power consumption of electronic equipments have been advanced, transparent oxide semiconductors and transparent conductive oxides have been drawing attention in a field of display. In particular, since a film can be formed on a resin film at low temperatures, future application to a lightweight portable electronic equipment and the like is expected.
As disclosed in Japanese Patent Application Laid-open No. 2004-103957, oxide films containing In, Ga, and Zn are optically transparent, and are also widely studied for application to transparent electrodes, transistors, and the like by reducing the resistance. Further, H. M. Kim et al., Jpn. J. Appl. Phys. Vol. 42, 2003, p. 223-227 and R. E. Presley et al., Vol. 50, Issue 3, March 2006, p. 500-503 disclose that reports have been made on researches on oxide films containing In and Zn or oxide films containing In and Ga.
In addition, researches and developments on oxide films containing In, Ga, and Zn and growing conditions of the films have also been made. In addition, production of a semiconductor device using an oxide film containing In, Ga, and Zn on a plastic film is reported by Chienliu Chang, et al. in Extended Abstracts of the 53th Spring Meeting of The Japan Society of Applied Physics and Related Societies, 22a-P1-45/II, p. 653, (2006).
Heretofore, patterning of produced oxide films containing In, Ga, and Zn, oxide films containing Ga and Zn, and oxide films containing In and Zn have been performed by the lift-off process. The lift-off process is disclosed in K. Nomura et al., Nature, Vol. 432, 25 Nov. 2004, p. 488-492, E. M. C. Fortunato et al., Advanced Materials, 2005, 17, No. 5, p. 590-594, P. Barquinha et al., Journal of Non-Crystalline Solid Vol. 352, Issues 9-20, 2006, pp. 1749-1752, etc.
For concise description, an oxide film containing In, Ga, and Zn (In—Ga—Zn oxide) is hereinafter referred to as IGZO. Similarly, an oxide film containing In and Zn (In—Zn oxide) is hereinafter referred to as IZO. Similarly, an oxide film containing In and Ga (In—Ga oxide) is hereinafter referred to as IGO. When semiconductor devices are produced using these transparent oxide semiconductors as an active layer, indium-tin oxide (ITO) films are generally used as a transparent conductive electrode.
In Japanese Patent Application Laid-open Nos. S58-120780 and S60-217636, and Japanese Patent Publication No. H04-5756, at least one kind of sulfuric acid, hydrochloric acid, nitric acid, and ferric chloride is used as a wet etching liquid (also referred to as “etchant”) of ITO. In Japanese Patent Application Laid-open No. 2005-258115, oxalic acid, a mixed acid of phosphoric acid, acetic acid, and nitric acid, an aqueous cerium ammonium nitrate solution, or the like is used as an etching liquid (also referred to as “etchant”) of IZO.